U.S. patent application number 10/874534 was filed with the patent office on 2004-12-30 for liquid crystal dispensing system using spacer information and method of dispensing liquid crystal material using the same.
This patent application is currently assigned to LG.Philips LCD Co., Ltd.. Invention is credited to Kwak, Soo-Min, Ryu, Joung-Ho, Son, Hae-Joon.
Application Number | 20040261895 10/874534 |
Document ID | / |
Family ID | 36959764 |
Filed Date | 2004-12-30 |
United States Patent
Application |
20040261895 |
Kind Code |
A1 |
Ryu, Joung-Ho ; et
al. |
December 30, 2004 |
Liquid crystal dispensing system using spacer information and
method of dispensing liquid crystal material using the same
Abstract
A liquid crystal dispensing system includes a container, a
discharge pump, a nozzle, and a control unit. The discharge pump
draws in and discharges liquid crystal that is contained in the
container. The nozzle dispenses the liquid crystal discharged from
the discharge pump onto a substrate. The control unit determines a
dispensing amount of liquid crystal based on a spacer height formed
at the substrate and to control the discharge pump in order to
dispense the determined amount of liquid crystal onto the
substrate.
Inventors: |
Ryu, Joung-Ho; (Seoul,
KR) ; Kwak, Soo-Min; (Gumi, KR) ; Son,
Hae-Joon; (Busan, KR) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Assignee: |
LG.Philips LCD Co., Ltd.
|
Family ID: |
36959764 |
Appl. No.: |
10/874534 |
Filed: |
June 24, 2004 |
Current U.S.
Class: |
141/95 |
Current CPC
Class: |
G02F 1/13415 20210101;
G02F 1/1341 20130101 |
Class at
Publication: |
141/095 |
International
Class: |
B65B 001/30 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 24, 2003 |
KR |
41275/2003 |
Claims
What is claimed is:
1. A liquid crystal dispensing system, comprising: a container to
contain liquid crystal; a discharge pump to draw in and discharge
liquid crystal from the container; a nozzle to dispense the liquid
crystal discharged from the discharge pump onto a substrate; and a
control unit to determine a dispensing amount of liquid crystal
based on a spacer height formed at the substrate and to control the
discharge pump in order to dispense the determined amount of liquid
crystal onto the substrate.
2. The liquid crystal dispensing system according to claim 1,
wherein the discharge pump includes: a cylinder; a piston, inserted
into the cylinder and having a groove at a lower portion, to draw
in and discharge liquid crystal in accordance with a rotational and
up-down motion; and a suction opening and a discharge opening to
respectively draw in and discharge liquid crystal accordingly as
the piston moves.
3. The liquid crystal dispensing system according to claim 2,
further comprising a fixing unit to fix the discharge pump.
4. The liquid crystal dispensing system according to claim 3,
wherein the fixing unit includes a rotating member to which the
piston of the discharge pump is fixed to rotate the piston.
5. The liquid crystal dispensing system according to claim 4,
wherein the piston is provided with a bar, the rotating member is
provided with a hole, and the bar is rotatably inserted into the
hole to fix the piston with the rotating member.
6. The liquid crystal dispensing system according to claim 4,
wherein a liquid crystal capacity amount of the discharge pump is
varied according to a fixation angle of the piston to the rotating
member.
7. The liquid crystal dispensing system according to claim 1,
further comprising a liquid crystal capacity amount controlling
member contacting the discharge pump to vary a fixation angle of
the discharge pump in order to control a liquid crystal discharge
amount.
8. The liquid crystal dispensing system according to claim 7,
further comprising: a motor to drive the liquid crystal capacity
amount controlling member; and a rotational shaft screw-coupled to
the liquid crystal capacity amount controlling member to be rotated
as the motor is driven in order to linearly move the liquid crystal
capacity amount controlling member.
9. The liquid crystal dispensing system according to claim 8,
wherein the motor includes one of a servo motor and a step
motor.
10. The liquid crystal dispensing system according to claim 1,
further comprising: a first connecting tube connecting the
container and the discharge pump; and a pin at the end of the first
connecting tube and inserted into a pad formed at the container to
introduce liquid crystal to the container.
11. The liquid crystal dispensing system according to claim 1,
further comprising a second connecting tube connecting the
discharge pump and the nozzle.
12. The liquid crystal dispensing system according to claim 11,
wherein the second connecting tube is formed of a transparent
material.
13. The liquid crystal dispensing system according to claim 12,
further comprising a first sensor installed near the second
connecting tube to detect whether vapor is contained in liquid
crystal discharged from the discharge pump.
14. The liquid crystal dispensing system according to claim 1,
further comprising a second sensor installed near the nozzle to
detect whether liquid crystal is massed on the surface of the
nozzle.
15. The liquid crystal dispensing system according to claim 1,
wherein the spacer is a pattern spacer.
16. The liquid crystal dispensing system according to claim 1,
wherein the substrate includes a plurality of liquid crystal panels
having different sizes.
17. The liquid crystal dispensing system according to claim 16,
wherein the dispensing amount of liquid crystal is calculated based
on a height of a spacer formed at a liquid crystal panel.
18. The liquid crystal dispensing system according to claim 1,
wherein the control unit includes: a height inputting unit to input
a height of a spacer formed at a substrate; a dispensing amount
calculating unit to calculate a dispensing amount of liquid crystal
to be dispensed onto a substrate; and a motor driving unit to drive
a motor in order to operate a discharge pump.
19. The liquid crystal dispensing system according to claim 18,
further comprising a substrate driving unit to drive a substrate in
order to align a nozzle at a dispensing position of liquid
crystal.
20. The liquid crystal dispensing system according to claim 18,
wherein the motor driving unit includes: a pulse value storing unit
to store pulse value information regarding a dispensing amount of
liquid crystal; and a pulse value converting unit to convert a
calculated dispensing amount value input from the dispensing amount
calculating unit into a pulse value based on the pulse value
information stored in the pulse value storing unit.
21. A liquid crystal dispensing system, comprising: a liquid
crystal dispenser having a container to contain liquid crystal, a
cylinder having a suction opening and a discharge opening, a
discharge pump to draw in and discharging liquid crystal contained
in the container through the suction opening and the discharge
opening by being inserted into the cylinder and by moving up-down,
and a nozzle to dispense the liquid crystal discharged from the
discharge pump onto a substrate; and a control unit to calculate a
dispensing amount of liquid crystal to be dispensed onto the
substrate based on a spacer height formed on the substrate and to
control the discharge pump.
22. A liquid crystal dispensing system, comprising: a liquid
crystal dispenser having a container to contain liquid crystal, a
discharge pump having a piston to draw in and discharge liquid
crystal contained in the container by an up-down motion of the
piston, and a nozzle to dispense liquid crystal discharged from the
discharge pump onto a multi-model substrate for fabricating a
plurality of liquid crystal panels of different sizes; and a
control unit to calculate a dispensing amount of liquid crystal to
be dispensed onto the plurality of liquid crystals panels based on
a spacer height formed at the liquid crystal panel of the
substrate, and to control the discharge pump in order to
sequentially dispense liquid crystal onto the plurality of liquid
crystal panels.
23. A method of dispensing liquid crystal material, comprising:
inputting a spacer height formed on a substrate; calculating a
dispensing amount of liquid crystal to be dispensed onto the
substrate based on the spacer height; aligning a liquid crystal
dispenser at a dispensing position, the liquid crystal dispenser
including a container containing liquid crystal, a discharge pump
having a piston to draw in and discharge liquid crystal contained
in the container by an up-down motion of the piston, and a nozzle
to dispensing liquid crystal discharged from the discharge pump
onto a multi-model substrate for fabricating a plurality of liquid
crystal panels of different sizes; and dispensing the calculated
amount of liquid crystal onto the substrate.
24. The method according to claim 23, further comprising driving a
second motor to adjust a fixation angle of the discharge pump to
discharge the calculated amount of liquid crystal.
25. The method according to claim 23, wherein dispensing liquid
crystal onto the substrate includes driving a first motor to
operate the piston.
26. The method according to claim 23, further comprising: forming a
spacer on a substrate; and measuring a height of the formed
spacer.
27. The method according to claim 26, wherein the spacer is formed
in a TFT process or a color filter process.
28. The method according to claim 27, wherein the spacer height is
measured in a TFT process or a color filter process.
29. The method according to claim 23, wherein the spacer is a
pattern spacer.
30. The method according to claim 23, wherein the substrate
includes a plurality of liquid crystal panels having different
sizes.
31. The method according to claim 23, wherein calculating a
dispensing amount of liquid crystal includes calculating a
dispensing amount of liquid crystal based on a spacer height formed
at each liquid crystal panel.
32. A method of dispensing liquid crystal material, comprising:
preparing a substrate including a plurality of liquid crystal
panels having different sizes; inputting a spacer height formed at
the liquid crystal panel; calculating a dispensing amount of liquid
crystal to be dispensed on the liquid crystal panel based on the
spacer height; aligning a liquid crystal dispenser at a dispensing
position of a corresponding liquid crystal panel, the liquid
crystal dispenser including a container containing liquid crystal,
a discharge pump having a piston that draws in and discharges
liquid crystal contained in the container by an up-down motion of
the piston, and a nozzle that dispenses liquid crystal discharged
from the discharge pump onto a multi-model substrate on which
including a plurality of liquid crystal panels of different sizes;
dispensing the calculated amount of liquid crystal onto the
substrate; and aligning the liquid crystal dispenser at a
dispensing position of the next liquid crystal panel on which
liquid crystal is to be dispensed.
33. A method of manufacturing a liquid crystal display device using
the liquid crystal dispensing system according to claim 1, the
method comprising: providing a first substrate; dispensing liquid
crystal from the liquid crystal dispensing system; and joining the
first substrate with a second substrate.
34. A method of manufacturing a liquid crystal display device using
the liquid crystal dispensing system according to claim 1, the
method comprising: providing a first substrate; dispensing liquid
crystal from the liquid crystal dispensing system; and joining the
first substrate with a second substrate.
35. A method of manufacturing a liquid crystal display device using
the liquid crystal dispensing system according to claim 21, the
method comprising: providing a first substrate; dispensing liquid
crystal from the liquid crystal dispensing system; and joining the
first substrate with a second substrate.
36. A method of manufacturing a liquid crystal display device using
the liquid crystal dispensing system according to claim 22, the
method comprising: providing a first substrate; dispensing liquid
crystal from the liquid crystal dispensing system; and joining the
first substrate with a second substrate.
Description
[0001] The present application claims the benefit of Korean Patent
Application No. 2003-41275 filed in Korea on Jun. 24, 2003. The
present application further incorporates by reference U.S. patent
application Ser. No. 10/421,714, which has published as US Patent
Publication No. 2004-0011422-A1.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a liquid crystal dispensing
system, and more particularly, to a liquid crystal dispensing
system for dispensing a precise amount of liquid crystal onto
liquid crystal panels having different sizes formed on a
multi-model glass substrate.
[0004] 2. Description of the Related Art
[0005] Recently, various portable electric devices, such as mobile
phones, personal digital assistants (PDAs), and notebook computers,
have been developed because of their small size, light weight, and
power-efficient operations. Accordingly, flat panel display
devices, such as liquid crystal displays (LCDs), plasma display
panels (PDPs), field emission displays (FEDs), and vacuum
fluorescent displays (VFDs), have been developed. Of these flat
panel display devices, the LCDs are currently mass produced because
of their simple driving scheme and superior image quality.
[0006] FIG. 1 is a cross sectional view of an LCD device according
to the related art. In FIG. 1, an LCD device 1 comprises a lower
substrate 5, an upper substrate 3, and a liquid crystal layer 7
formed therebetween. The lower substrate 5 is a driving device
array substrate, and includes a plurality of pixels (not shown) and
a driving device, such as a thin film transistor (TFT), formed on
each pixel. The upper substrate 3 is a color filter substrate, and
includes a color filter layer for reproducing real color. In
addition, a pixel electrode and a common electrode are formed on
the lower substrate 5 and the upper substrate 3, respectively. An
alignment layer is formed on both the lower and upper substrates 5
and 3 to align liquid crystal molecules of the liquid crystal layer
7. The lower substrate 5 and the upper substrate 3 are attached
along a perimeter by a sealant 9, and the liquid crystal 7 is
confined within the perimeter. In operation, the liquid crystal
molecules of the liquid crystal layer 7 are reoriented by the
driving device formed on the lower substrate 5 to control amounts
of light transmitted through the liquid crystal layer 7, thereby
displaying an image.
[0007] FIG. 2 is a flow chart of a fabrication method for an LCD
device according to the related art. In FIG. 2, a fabrication
method includes three sub-processes for manufacturing an LCD
device: a driving device array substrate process for forming the
driving device on the lower substrate 5; a color filter substrate
process for forming the color filter on the upper substrate 3; and
a cell process.
[0008] In Step S101, a plurality of gate lines and data lines are
formed on the lower substrate 5 to define a pixel area by the
driving device array process, and the thin film transistor
connected to both the gate line and the data line is formed on the
each pixel area. In addition, a pixel electrode, which is to be
connected to the thin film transistor to drive the liquid crystal
layer according to a signal applied through the thin film
transistor, is formed by the driving device array process. In Step
S104, R, G, and B color filter layers for reproducing the color and
a common electrode are formed on the upper substrate 3 by the color
filter process.
[0009] In Steps S102 and S105, alignment layers are formed on the
lower substrate 5 and the upper substrate 3. Then, the alignment
layers are individually rubbed to induce surface anchoring (i.e. a
pretilt angle and an alignment direction) for the liquid crystal
molecules of the liquid crystal layer 7. In Step S103, a spacer is
dispersed onto the lower substrate 5 for maintaining a uniform cell
gap between the lower and upper substrates 5 and 3. In Step S106, a
sealant is printed along outer portions of the upper substrate
3.
[0010] In Step S107, the lower and upper substrates 5 and 3 are
assembled together by compression. The lower substrate 5 and the
upper substrate 3 are both made of glass substrates, and include a
plurality of unit panel areas on which the driving device and the
color filter layer are formed. In Step S108, the assembled upper
and lower glass substrates 5 and 3 are cut into unit panels. In
Step S109, liquid crystal material is injected into the gap formed
between the upper and lower substrates 5 and 3 of the unit panels
through a liquid crystal injection hole. The filled unit panel is
completed by sealing the liquid crystal injection hole. In Step
S110, the filled and sealed unit panel is tested.
[0011] FIG. 3 is a schematic view of a liquid crystal injection
system for fabricating an LCD device according to the related art.
In FIG. 3, a container 12 in which liquid crystal material 14 is
contained is placed in a vacuum chamber 10, and the liquid crystal
display panel 1 is located at an upper side of the container 12.
Then, the vacuum chamber 10 is connected to a vacuum pump (not
shown) to maintain a predetermined vacuum/pressure state within the
vacuum chamber 10. In addition, a liquid crystal display panel
moving device (not shown) is installed in the vacuum chamber 10 to
move the liquid crystal display panel 1 from the upper side of the
container 12 to a surface of the liquid crystal material 14,
thereby contacting an injection hole 16 of the liquid crystal
display panel 1 to the liquid crystal material 14. Accordingly,
this method is commonly called as a liquid crystal dipping
injection method.
[0012] When the vacuum/pressure level within the chamber 10 is
decreased by an inflow of nitrogen gas (N.sub.2) into the vacuum
chamber 10 in the state that the injection hole 16 of the liquid
crystal display panel 1 contacts the surface of the liquid crystal
material 14, the liquid crystal material 14 is injected into the
liquid crystal display panel 1 through the injection hole 16 by the
pressure difference between the vacuum/pressure level within the
liquid crystal display panel 1 and the pressure/level within the
vacuum chamber 10. After the liquid crystal material 14 is
completely filled into the liquid crystal display panel 1, the
injection hole 16 is sealed by a sealant to seal the liquid crystal
material 14 within the liquid crystal display panel 1. Accordingly,
this method is called as a vacuum injection method.
[0013] However, there are several problems with both the liquid
crystal dipping injection method and vacuum injection method.
First, an overall time for injection of the liquid crystal material
14 into the panel 1 is relatively long for either method. In
general, a gap between the driving device array substrate and the
color filter substrate in the liquid crystal display panel 1 is
relatively narrow, i.e., a few micrometers. Accordingly, a
relatively small amount of liquid crystal material 14 is injected
into the liquid crystal display panel 1 per unit time. For example,
it takes about 8 hours to completely inject the liquid crystal
material 14 into a 15-inch liquid crystal display panel, and thus,
fabricating efficiency is decreased. Second, consumption of the
liquid crystal material 14 during the liquid crystal injection
method is large. Only a small amount of the liquid crystal material
14 in the container 12 is actually injected into the liquid crystal
display panel 1. Accordingly, during loading of the liquid crystal
display panel 1 into the vacuum chamber 10, the unused liquid
crystal material 14 is exposed to atmosphere or to certain gases,
thereby contaminating the liquid crystal material 14. Thus, any
remaining liquid crystal material 14 must be discarded after the
injection of the liquid crystal material 14 into a plurality of
liquid crystal display panels 1, thereby increasing fabricating
costs.
SUMMARY OF THE INVENTION
[0014] Accordingly, the present invention is directed to a liquid
crystal dispensing system and method of dispensing liquid crystal
material using the same that substantially obviates one or more of
the problems due to limitations and disadvantages of the related
art.
[0015] Therefore, an object of the present invention is to provide
a liquid crystal dispensing system to directly dispense liquid
crystal onto a glass substrate of a large area including at least
one liquid crystal panel, and a method of dispensing liquid crystal
material using the same.
[0016] Another object of the present invention is to provide a
liquid crystal dispensing system that prevents inferior LCD devices
by always dispensing a precise amount of liquid crystal by
calculating a dispensing amount of liquid crystal based on a spacer
height formed on a substrate, and a method of dispensing liquid
crystal material using the same.
[0017] Still another object of the present invention is to provide
a liquid crystal dispensing system capable of dispensing a precise
amount of liquid crystal onto a substrate having a plurality of
liquid crystal panels of different sizes, and a method of
dispensing liquid crystal material using the same.
[0018] Additional features and advantages of the invention will be
set forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of the
invention. The objectives and other advantages of the invention
will be realized and attained by the structure particularly pointed
out in the written description and claims hereof as well as the
appended drawings.
[0019] To achieve these and other advantages and in accordance with
the purpose of the present invention, as embodied and broadly
described herein, a liquid crystal dispensing system comprises a
container to contain liquid crystal; a discharge pump to draw in
and discharge liquid crystal from the container; a nozzle to
dispense the liquid crystal discharged from the discharge pump onto
a substrate; and a control unit to determine a dispensing amount of
liquid crystal based on a spacer height formed at the substrate and
to control the discharge pump in order to dispense the determined
amount of liquid crystal onto the substrate.
[0020] In another aspect, a liquid crystal dispensing system
comprises a liquid crystal dispenser having a container to contain
liquid crystal, a cylinder having a suction opening and a discharge
opening, a discharge pump to draw in and discharging liquid crystal
contained in the container through the suction opening and the
discharge opening by being inserted into the cylinder and by moving
up-down, and a nozzle to dispense liquid crystal discharged from
the discharge pump onto a substrate; and a control unit to
calculate a dispensing amount of liquid crystal to be dispensed
onto the substrate based on a spacer height formed on the substrate
and to control the discharge pump.
[0021] In another aspect, a liquid crystal dispensing system
comprises a liquid crystal dispenser having a container to contain
liquid crystal, a discharge pump having a piston to draw in and
discharge liquid crystal contained in the container by an up-down
motion of the piston, and a nozzle to dispense the liquid crystal
discharged from the discharge pump onto a multi-model substrate for
fabricating a plurality of liquid crystal panels of different
sizes; and a control unit to calculate a dispensing amount of
liquid crystal to be dispensed onto the plurality of liquid
crystals panels based on a spacer height formed at the liquid
crystal panel of the substrate, and to control the discharge pump
in order to sequentially dispense liquid crystal onto the plurality
of liquid crystal panels.
[0022] In another aspect, a method of dispensing liquid crystal
material comprises inputting a spacer height formed on a substrate;
calculating a dispensing amount of liquid crystal to be dispensed
onto the substrate based on the spacer height; aligning a liquid
crystal dispenser at a dispensing position, the liquid crystal
dispenser including a container containing liquid crystal, a
discharge pump having a piston to draw in and discharge liquid
crystal contained in the container by an up-down motion of the
piston, and a nozzle to dispensing liquid crystal discharged from
the discharge pump onto a multi-model substrate for fabricating a
plurality of liquid crystal panels of different sizes; and
dispensing the calculated amount of liquid crystal onto the
substrate.
[0023] In another aspect, a method of dispensing liquid crystal
material comprises preparing a substrate including a plurality of
liquid crystal panels having different sizes; inputting a spacer
height formed at the liquid crystal panel; calculating a dispensing
amount of liquid crystal to be dispensed on the liquid crystal
panel based on the spacer height; aligning a liquid crystal
dispenser at a dispensing position of a corresponding liquid
crystal panel, the liquid crystal dispenser including a container
containing liquid crystal, a discharge pump having a piston that
draws in and discharges liquid crystal contained in the container
by an up-down motion of the piston, and a nozzle that dispenses
liquid crystal discharged from the discharge pump onto a
multi-model substrate on which including a plurality of liquid
crystal panels of different sizes; dispensing the calculated amount
of liquid crystal onto the substrate; and aligning the liquid
crystal dispenser at a dispensing position of the next liquid
crystal panel on which liquid crystal is to be dispensed.
[0024] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention. In the drawings:
[0026] FIG. 1 is a cross sectional view of a liquid crystal display
(LCD) device according to the related art;
[0027] FIG. 2 is a flow chart of a fabrication method for an LCD
device according to the related art;
[0028] FIG. 3 is a schematic view of a liquid crystal injection
system for fabricating an LCD device according to the related
art;
[0029] FIG. 4 is a cross sectional view of an LCD device fabricated
by a liquid crystal dispensing method according to an embodiment of
the present invention;
[0030] FIG. 5 is a flow chart of a fabrication method of an LCD
device by a liquid crystal dispensing method according to an
embodiment of the present invention;
[0031] FIG. 6 is a view of a basic concept of a liquid crystal
dispensing method;
[0032] FIG. 7 is a perspective view of a liquid crystal dispenser
according to an embodiment of the present invention;
[0033] FIG. 8 is a disassembled perspective view of the liquid
crystal dispenser according to an embodiment of the present
invention;
[0034] FIG. 9A is a perspective view of a liquid crystal discharge
pump of the liquid crystal dispenser according to an embodiment of
the present invention;
[0035] FIG. 9B is a disassembled perspective view of the liquid
crystal discharge pump of FIG. 9A;
[0036] FIG. 10 is a view showing a state that the liquid crystal
discharge pump is fixed to a fixing unit;
[0037] FIGS. 11A to 11D are operational views of the liquid crystal
discharge pump;
[0038] FIG. 12 is a view of the liquid crystal discharge pump of
which a fixation angle has been increased;
[0039] FIG. 13 is a block diagram of a control unit of a liquid
crystal dispensing system according to an embodiment of the present
invention;
[0040] FIG. 14 is a block diagram of a motor driving unit according
to an embodiment of the present invention; and
[0041] FIG. 15 is a flow chart showing a liquid crystal dispensing
method according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings.
[0043] To solve the problems of the related liquid crystal
injection methods such as a liquid crystal dipping method or a
liquid crystal vacuum injection method, a liquid crystal dispensing
method has been recently introduced. The liquid crystal dispensing
method is a method for forming a liquid crystal layer by directly
dropping the liquid crystal onto the substrates and spreading the
dropped liquid crystal over the entire panel by pressing together
the substrates during the assembling procedure of the substrates
rather than by injecting the liquid crystal into the empty unit
panel by the pressure difference between the inner and outer sides
of the panel. According to the above liquid crystal dispensing
method, the liquid crystal is directly dropped onto the substrate
in a short time period so that the liquid crystal layer in a LCD of
larger area can be formed quickly. In addition, the liquid crystal
consumption can be minimized due to the direct dropping of the
liquid crystal as much as required amount, and therefore, the
fabrication cost can be reduced.
[0044] FIG. 4 is a view illustrating a basic concept of a liquid
crystal dispensing method according to an embodiment of the present
invention. In FIG. 4, liquid crystal material 107 may be dropped
onto a lower substrate 105 having a driving device prior to
assembling the lower substrate 105 and an upper substrate 103
having a color filter. Alternatively, the liquid crystal material
107 may be dropped onto the upper substrate 103 upon which the
color filter is formed. For example, the liquid crystal material
107 may be formed either on a thin film transistor (TFT) substrate
or on a color filter (CF) substrate.
[0045] A sealant 109 may be applied along at least an outer
perimeter portion of the upper substrate 103. Then, the upper
substrate 103 and the lower substrate 105 may be assembled together
by pressing the upper and lower substrates 103 and 105 together to
form an LCD display panel 101. Accordingly, the drops of the liquid
crystal material 107 spread out between the upper and lower
substrates 103 and 105 by pressure applied to the upper and/or
lower substrates 103 and 105, thereby forming a liquid crystal
material layer of uniform thickness between the upper substrate 103
and the lower substrate 105. Thus, in the exemplary LCD device
fabrication method, the liquid crystal material 107 may be dropped
onto the lower substrate 105 before the upper and lower substrates
103 and 105 are assembled together to form the LCD display panel
101.
[0046] FIG. 5 is a flow chart of an exemplary LCD device
fabrication method according to an embodiment of the present
invention. In Step S201, a driving device, such as a TFT, is formed
on an upper substrate using a TFT array process. In Step S204, a
color filter layer is formed on a lower substrate 105 using a color
filter process. The TFT array process and the color filter process,
which are generally similar to those of common processes, may be
preferably applied to glass substrates having a plurality of unit
panel areas. Herein, the upper and lower substrates may include a
glass substrate having an area about 1000.times.1200 mm.sup.2 or
more. However, glass substrates having smaller areas also may be
used.
[0047] In Steps S202 and S205, alignment layers may be formed and
rubbed on both the upper and lower substrates. In Step S203, liquid
crystal material 107 may be dropped onto a liquid crystal display
unit panel area of the lower substrate 105. In Step S206, sealant
109 is applied along at least an outer perimeter portion area of
the liquid crystal display unit panel area on the upper
substrate.
[0048] In Step S207, the upper and lower substrates are disposed to
face each other, and compressed to join the upper and lower
substrates with each other using the sealant 109. Accordingly, the
dropped liquid crystal material evenly spreads out between the
upper and lower substrates and the sealant 109. In Step S208, the
assembled upper and lower substrates are processed and cut into a
plurality of liquid crystal display unit panels. In Step S209, the
liquid crystal display unit panels are tested.
[0049] The LCD device fabrication method using the liquid crystal
dropping method of FIG. 5 is different from the LCD device
fabrication method using the related art liquid crystal injection
method in that a vacuum injection of liquid crystal is not used but
rather a liquid crystal dropping, thereby reducing the processing
time of a large area glass substrate. That is, in the LCD device
fabrication method using the liquid crystal injection method of
FIG. 2, liquid crystal is injected through an injection hole and
then the injection hole is sealed by a sealant. However, in the LCD
device fabrication method using the liquid crystal dropping method,
liquid crystal is directly dropped onto the substrate and does not
require the process sealing of the injection hole. Although not
shown in FIG. 2, in the LCD device fabrication method using the
liquid crystal injection method, the substrate is contacting the
liquid crystal at the time of injecting liquid crystal so that an
outer surface of the panel is contaminated by the liquid crystal.
Therefore, a process for washing the contaminated substrate is
required. However, in the LCD device fabrication method using the
liquid crystal dropping method, liquid crystal is directly dropped
onto the substrate so that the panel is not contaminated by the
liquid crystal, and a washing process is not required. The LCD
device fabrication method using the liquid crystal dropping method
is more simple than the LCD device fabrication method using the
liquid crystal injection method, thereby having an increased
fabricating efficiency and an increased yield.
[0050] In the LCD device fabrication method using the liquid
crystal dropping method, a dropping position of liquid crystal and
a dropping amount of liquid crystal have the most influence on
forming a liquid crystal layer with a desired thickness.
Especially, since the thickness of a liquid crystal layer is
closely related to a cell gap of a liquid crystal panel, a precise
dropping position of liquid crystal and a precise amount of liquid
crystal are very important to prevent inferiority of a liquid
crystal panel. To drop a precise amount of liquid crystal onto a
precise position, a liquid crystal dispenser is provided in the
present invention.
[0051] FIG. 6 is a view illustrating the basic concept of a liquid
crystal dispensing method. In FIG. 6, liquid crystal material 107
is dispensed onto a glass substrate 105 using a liquid crystal
dispenser 120 positioned above the glass substrate 105. Although
not shown, the liquid crystal material 107 may be contained in the
liquid crystal dispenser 120. As the liquid crystal material 107 is
dropped onto the glass substrate 105, the glass substrate 105 is
moved along x- and y-directions at a predetermined speed, while the
liquid crystal dispenser 120 discharges the liquid crystal material
107 at predetermined time intervals. Accordingly, the liquid
crystal material 107 dropping onto the glass substrate 105 may be
arranged along x- and y-directions with predetermined intervals
therebetween. Alternatively, the glass substrate 105 may be fixed
while the liquid crystal dispenser 120 moves along the x- and
y-directions to drop the liquid crystal material 107 at
predetermined intervals. However, a shape of the liquid crystal
material 107 may be altered by any vibration of the liquid crystal
dispenser 120, whereby errors in the dropping position and the
dropping amount of the liquid crystal material 107 may occur.
Therefore, it may be preferable that the liquid crystal dispenser
120 be fixed and that the glass substrate 105 be moved.
[0052] FIG. 7 is a perspective view of the liquid crystal dispenser
according to an embodiment of the present invention, and FIG. 8 is
a disassembled perspective view of the liquid crystal dispenser
according to an embodiment of the present invention. In FIGS. 7A
and 7B, the liquid crystal dispenser 120 may include a
cylindrically shaped liquid crystal material container 122
accommodated in a case 123. The liquid crystal material container
122 is formed of polyethylene, and the liquid crystal 107 is
contained in the liquid crystal material container 122. The case
123 is formed of stainless steel and accommodates the liquid
crystal material container 122 therein. Since the polyethylene has
a high plasticity, a container of a desired shape can be easily
formed with the polyethylene. Also, the polyethylene is
non-reactive with the liquid crystal material 107 when the liquid
crystal material 107 is contained therein, thereby being mainly
used as the liquid crystal material container 122. However, the
polyethylene has a low strength and may therefore become easily
deformed by application of stress. When the liquid crystal material
container 122 is deformed, the liquid crystal material 107 may not
be precisely dispensed onto a substrate. Accordingly, the liquid
crystal material container 122 may be inserted within the case 123
formed of stainless steel having a high strength.
[0053] Although not shown, a gas supply tube may be arranged at an
upper portion of the liquid crystal material container 122 so that
inert gas, such as nitrogen, may be provided thereto. The gas is
supplied within portions of the liquid crystal material container
122 not occupied by the liquid crystal material 107. Accordingly,
the gas presses on the liquid crystal material 107 and induces the
liquid crystal material to be dispensed onto the substrate.
[0054] The liquid crystal material container 122 may include a
material that does not deform, such as stainless steel.
Accordingly, when the liquid crystal material container 122 is
formed of stainless steel, the case 123 may not be required,
thereby reducing fabrication costs of the liquid crystal dispenser
120. The interior of the liquid crystal material container 122 may
be coated with a fluorine resin, thereby preventing the liquid
crystal material 107 contained within the liquid crystal material
container 122 from chemically reacting with sidewalls of the liquid
crystal material container 122.
[0055] A liquid crystal discharge pump 140 is arranged at a lower
portion of the liquid crystal material container 122. The liquid
crystal discharge pump 140 is for discharging a certain amount of
liquid crystal from the liquid crystal material container 122 to be
dropped onto a substrate. The liquid crystal discharge pump 140 is
provided with a liquid crystal suction opening 147 connected to the
liquid crystal material container 122 for drawing in liquid crystal
in accordance with the operation of the liquid crystal discharge
pump 140, and a liquid crystal discharge opening 148 at the
opposite side of the liquid crystal suction opening 147 for
discharging liquid crystal in accordance with the operation of the
liquid crystal discharge pump 140.
[0056] In FIG. 8, a first connecting tube 126 is coupled to the
liquid crystal suction opening 147. Although the liquid crystal
suction opening 147 is coupled to the first connecting tube 126 by
being inserted in the drawing, the liquid crystal suction opening
147 can be coupled to the first connecting tube 126 by a coupling
member such as a screw. A pin 128 such as an injection needle of
which inside is penetrated is formed at one side of the first
connecting tube 126. A pad (not shown) formed of a material having
a high contraction characteristic and a hermetic characteristic
such as silicon or butyl rubber group material is arranged at a
lower portion of the liquid crystal material container 122 for
discharging liquid crystal to the first connecting tube 126. The
pin 128 is inserted into the liquid crystal material container 122
through the pad, thereby introducing the liquid crystal 107 of the
liquid crystal material container 122 into the liquid crystal
suction opening 147. When the pin 128 is inserted into the liquid
crystal material container 122, the pad forms a seal around the pin
128, thereby preventing leakage of the liquid crystal 107 to the
insertion region of the pin 128. Since the liquid crystal suction
opening 147 and the liquid crystal material container 122 are
coupled to each other by the pin and the pad, the coupling
structure is simple and the coupling/detachment is facilitated.
Alternatively, the liquid crystal suction opening 147 and the first
connecting tube 126 may be formed as a unit. In this case, the pin
128 is formed at the liquid crystal suction opening 147 and is
directly inserted into the liquid crystal material container 122 to
discharge liquid crystal, thereby having a simple structure.
[0057] A nozzle 150 is formed at a lower portion of the liquid
crystal discharge pump 140. The nozzle 150 is connected to the
liquid crystal discharge opening 148 of the liquid crystal
discharge pump 140 through a second connecting tube 160, thereby
dropping the liquid crystal 107 discharged from the liquid crystal
discharge pump 140 onto the liquid crystal panel of the substrate.
The second connecting tube 160 may be formed of an opaque material.
Alternatively, the second connecting tube 160 may be formed of a
transparent material due to the following reasons.
[0058] At the time of the liquid crystal dropping, vapor is
contained in the liquid crystal 107 and a dispensing amount of the
liquid crystal 107 dispensed onto the substrate can not be
precisely controlled. Therefore, the vapor has to be removed at the
time of the liquid crystal dropping. The vapor is already contained
in the liquid crystal 107 to be contained in the liquid crystal
material container 122. Even if the vapor contained in the liquid
crystal 107 can be removed by a vapor removing device, the vapor is
not completely removed. Also, vapor may be generated when the
liquid crystal 107 is introduced into the liquid crystal discharge
pump 140 from the liquid crystal material container 122.
Accordingly, it is impossible to completely remove the vapor
contained in the liquid crystal 107. Therefore, it preferred to
remove vapor by stopping the operation of the liquid crystal
dispenser at the time of the vapor occurrence. Thus by forming the
second connecting tube 160 of a transparent material, inferiority
of the LCD device can be prevented by easily finding vapor
contained in the liquid crystal material container 122 or vapor
generated from the liquid crystal material container 122. The vapor
can be found by the user's naked eyes, and can be automatically
detected by a first sensor 162 such as a photo coupler installed at
both sides of the second connecting tube 160, in which the latter
case can prevent the inferiority of the LCD device with more
certainty.
[0059] The nozzle 150 into which the discharged liquid crystal is
introduced through the second connecting tube 160 is provided with
a protection unit 152 for protecting the nozzle 150 from external
stress and etc. at both side surfaces thereof. Also, a second
sensor 154 for detecting whether vapor is contained in the liquid
crystal dropped from the nozzle 150 or whether liquid crystal
masses on the surface of the nozzle 150 is installed at the
protection unit 152 at the lower portion of the nozzle 150.
[0060] The phenomenon that the liquid crystal masses on the surface
of the nozzle 150 prevents a precise dropping of the liquid crystal
107. When the liquid crystal drops through the nozzle 150, a
certain amount of liquid crystal spreads on the surface of the
nozzle 150 even if a preset amount of liquid crystal is discharged
from the liquid crystal discharge pump 140. According to this, an
amount of liquid crystal less than the preset amount is dispensed
onto the substrate. Also, when the liquid crystal that masses on
the surface of the nozzle 150 drops on the substrate, inferiority
of the LCD device may be generated. To prevent the liquid crystal
from massing on the surface of the nozzle 150, material such as
fluorine resin having a high contact angle with liquid crystal,
that is a hydrophobic material, may be deposited on the surface of
the nozzle 150 by a dipping method or a spray method. By the
deposition of the fluorine resin, the liquid crystal does not
spread on the surface of the nozzle 150 but is dispensed onto the
substrate through the nozzle 150 as a perfect drop shape.
[0061] The liquid crystal discharge pump 140 is in a state of being
inserted into a rotating member 157, and the rotating member 157 is
fixed to a fixing unit 155. The rotating member 157 is connected to
a first motor 131. As the first motor 131 is operated, the rotating
member 157 is rotated and the liquid crystal discharge pump 140
fixed to the rotating member 157 is operated.
[0062] The liquid crystal discharge pump 140 is in contact with one
side of a liquid crystal capacity amount controlling member 134
having a bar shape. A hole is formed at another side of the liquid
crystal capacity amount controlling member 134, and a rotational
shaft 136 is inserted into the hole. A screw is provided at the
perimeter of the hole of the liquid crystal capacity amount
controlling member 134 and the rotational shaft 136 so that the
liquid crystal capacity amount controlling member 134 and the
rotational shaft 136 are screw-coupled to each other. One end of
the rotational shaft 136 is connected to a second motor 133, and
another end thereof is connected to a controlling lever 137.
[0063] The discharge amount of liquid crystal from the liquid
crystal material container 122 through the liquid crystal discharge
pump 140 is varied according to a fixation angle of the liquid
crystal discharge pump 140 to the rotating member 157. That is, a
liquid crystal capacity amount of the liquid crystal discharge pump
140 is varied according to an angle that the liquid crystal
discharge pump 140 is fixed to the rotating member 157. When the
second motor 133 connected to the rotational shaft 136 is driven
(automatically controlled) or the controlling lever 137 is operated
(manually controlled), the rotational shaft 136 is rotated.
According to this, one end of the liquid crystal capacity amount
controlling member 134 screw-coupled to the rotational shaft 136
moves back and forth (linear direction) along the rotational shaft
136. Accordingly, as one end of the liquid crystal capacity amount
controlling member 134 moves, a force applied to the liquid crystal
discharge pump 140 is varied, and therefore, the fixation angle of
the liquid crystal discharge pump 140 is varied.
[0064] As aforementioned, the first motor 131 operates the liquid
crystal discharge pump 140 to discharge liquid crystal of the
liquid crystal material container 122 and to drop the liquid
crystal onto the substrate. Also, the second motor 133 controls the
fixation angle of the liquid crystal discharge pump 140 fixed to
the rotating member 157 to control the amount of liquid crystal
discharged from the liquid crystal discharge pump 140.
[0065] A single dispensing amount of liquid crystal dropped onto
the substrate through the liquid crystal discharge pump 140 is very
minute, and therefore, a variation amount of the liquid crystal
discharge pump 140 controlled by the second motor 133 is also
minute. Accordingly, to control the discharge amount of the liquid
crystal discharge pump 140, an inclination angle of the liquid
crystal discharge pump 140 has to be controlled very precisely. For
the precise control, a servo motor or a step motor operated by a
pulse input value is used as the second motor 133.
[0066] FIG. 9A is a perspective view of the liquid crystal
discharge pump, and FIG. 9B is a disassembled perspective view of
the liquid crystal discharge pump. In FIGS. 9A and 9B, the liquid
crystal discharge pump 140 includes: a case 141 having the liquid
crystal suction opening 147 and the liquid crystal discharge
opening 148; a cap 144 having an opening at an upper portion
thereof and coupled to the case 141; a cylinder 142 inserted into
the case 141 for drawing in liquid crystal; a sealing member 143
for sealing the cylinder 142; an O-ring 144a positioned above the
cap 144 for preventing liquid crystal from being leaked; and a
piston 145 up-down moved and rotated by being inserted into the
cylinder 142 through the opening of the cap 144, for drawing in and
discharging the liquid crystal 107 through the liquid crystal
suction opening 147 and the liquid crystal discharge opening 148. A
head 146a fixed to the rotating member 157 is installed above the
piston 145, and a bar 146b is installed at the head 146a. The bar
146b is inserted into a hole (not shown) of the rotating member 157
and is fixed, thereby rotating the piston 145 when the rotating
member 157 is rotated by a force of the first motor 131.
[0067] In FIG. 9B, a groove 145a is formed at the end of the piston
145. The groove 145a has an area corresponding to approximately
{fraction (1/4)} (or less than that) of a sectional area of a
circle shape of the piston 145. The groove 145a opens and closes
the liquid crystal suction opening 147 and the liquid crystal
discharge opening 148 when the piston 145 is rotated (that is,
moved up and down), thereby drawing in and discharging liquid
crystal through the liquid crystal suction opening 147 and the
liquid crystal discharge opening 148.
[0068] Operation of the liquid crystal discharge pump 140 will be
explained as follows.
[0069] FIG. 10 is a view showing a state that the liquid crystal
discharge pump 140 is fixed to the rotating member 157. In FIG. 10,
the piston 145 is fixed to the rotating member 157 with a certain
angle (.alpha.). The bar 146b formed at the piston head 146a is
inserted into a hole 159 formed inside the rotating member 157 so
that the piston 145 and the rotating member 157 are coupled to each
other. Although not shown, a bearing is provided inside the hole
159 and thereby the bar 146b of the piston 145 inserted into the
hole 159 can move back and forth and right and left. When the first
motor 131 is operated, the rotating member 157 is rotated and
thereby the piston 145 coupled to the rotating member 157 is
rotated.
[0070] Herein, if the fixation angle (.alpha.) of the liquid
crystal discharge pump for the rotating member 157, that is, the
fixation angle (.alpha.) of the piston 145 for the rotating member
157 is supposed to be 0, the piston 145 performs only a rotational
motion along the rotating member 157. However, since the fixation
angle (.alpha.) of the piston 145 is not substantially zero (that
is, the piston 145 is fixed with a certain angle), the piston 145
not only rotates along the rotating member 157 but also up-down
moves.
[0071] If the piston 145 moves upwardly by rotating with a certain
angle, a space is formed inside the cylinder 142 and liquid crystal
is drawn into the space through the liquid crystal suction opening
147. Then, if the piston 145 moves downwardly by rotating more, the
liquid crystal in the cylinder 142 is discharged through the liquid
crystal discharge opening 148. Herein, the groove 145a formed at
the piston 145 opens and closes the liquid crystal suction opening
147 and the liquid crystal discharge opening 148 at the time of
sucking and discharging the liquid crystal by the rotation of the
piston 145.
[0072] Hereinafter, operation of the liquid crystal disc charge
pump 140 will be explained in more detail with reference to FIGS.
11A to 11D. In FIGS. 11A to 11D, the liquid crystal discharge pump
140 discharges the liquid crystal 107 of the liquid crystal
material container 122 to the nozzle 150 through 4 strokes. FIGS.
11A and 11C are cross strokes, FIG. 11B is a suction stroke through
the liquid crystal suction opening 147, and FIG. 11D is a discharge
stroke through the liquid crystal discharge opening 148.
[0073] In FIG. 11A, the piston 145 fixed to the rotating member 157
with a certain angle (a) rotates accordingly as the rotating member
157 rotates. At this time, the liquid crystal suction opening 147
and the liquid crystal discharge opening 148 are closed by the
piston 145.
[0074] When the rotating member 157 rotates with approximately
45.degree., the piston 145 rotates and the liquid crystal suction
opening 147 is open by the groove 145a of the piston 145 as shown
in FIG. 11B. The bar 146b of the piston 145 is inserted into the
hole 159 of the rotating member 157, thereby coupling the rotating
member 157 and the piston 145. Accordingly, as the rotating member
157 rotates, the piston 145 rotates. At this time, the bar 146b
rotates along a rotating plane.
[0075] Since the piston 145 is fixed to the rotating member 157
with a certain angle and the bar 146b rotates along the rotating
plane, the piston 145 moves upwardly accordingly as the rotating
member 157 rotates. Also, accordingly as the rotating member 157
rotates, a space is formed at the cylinder 142 positioned at the
lower portion of the piston 145 since the cylinder 142 is fixed.
Therefore, liquid crystal is drawn into the space through the
liquid crystal suction opening 147 that has been open by the groove
145a. The suction stroke of liquid crystal continues until the
suction stroke of FIG. 11C starts (the liquid crystal suction
opening 147 is closed) as the rotating member 157 rotates with
approximately 45.degree. after the suction stroke starts (that is,
the liquid crystal suction opening 147 is open).
[0076] Then, as shown in FIG. 11D, the liquid crystal discharge
opening 148 is open and the piston 145 downwardly moves accordingly
as the rotating member 157 rotates more so that the liquid crystal
sucked into the space inside the cylinder 142 is discharged through
the liquid crystal discharge opening 148 (discharge stroke). As
aforementioned, the liquid crystal discharge pump 140 repeats four
strokes (that is, the first cross stroke, the suction stroke, the
second cross stroke, and the discharge stroke), thereby discharging
the liquid crystal 107 contained in the liquid crystal material
container 122 to the nozzle 150. Herein, the discharge amount of
liquid crystal is varied according to an up-down motion range of
the piston 145. The up-down motion range of the piston 145 is
varied according to the angle of the liquid crystal discharge pump
140 fixed to the rotating member 157.
[0077] FIG. 12 shows a liquid crystal discharge pump 140 with the
piston 145 fixed to the rotating member 157 with an angle of
.beta.. When compared to the liquid crystal discharge pump 140 of
FIG. 10 having the piston 145 fixed to the rotating member 157 with
the angle of .alpha., the liquid crystal discharge pump 140 of FIG.
12 having the piston 145 fixed to the rotating member 157 with an
angle of .beta.(>.alpha.) enables the piston 145 to upwardly
move more highly. That is, the greater the angle of the liquid
crystal discharge pump 140 relative to the rotating member 157 is,
the greater the amount of the liquid crystal 107 drawn into the
cylinder 142 at the time of the piston motion is. This means that
the discharge amount of liquid crystal can be controlled by
adjusting the angle of the liquid crystal discharge pump 140 fixed
to the rotating member 157.
[0078] The angle of the liquid crystal discharge pump 140 fixed to
the rotating member 157 is controlled by the liquid crystal
capacity amount controlling member 134 of FIG. 7, and the liquid
crystal capacity amount controlling member 134 is moved by driving
the second motor 133. That is, the angle of the liquid crystal
discharge pump 140 fixed to the rotating member 157 is controlled
by controlling the second motor 133.
[0079] The fixation angle of the liquid crystal discharge pump 140
can be manually adjusted by handling the angle controlling lever
137 by the user. However, in this case, a precise adjustment is not
possible, a lot of time is required, and the driving of the liquid
crystal discharge pump has to be stopped during the operation.
Therefore, it is preferable to adjust the fixation angle of the
liquid crystal discharge pump 140 by the second motor 133. The
fixation angle of the liquid crystal discharge pump 140 is measured
by a sensor 139 such as a linear variable differential transformer.
If the fixation angle exceeds a preset angle, the sensor 139 rings
the alarm thus to prevent the liquid crystal discharge pump 140
from being damaged. Although not shown, the first motor 131 and the
second motor 133 are connected to a control unit by wire or
wirelessly. Each kind of information is input to the control unit
to calculate a dispensing amount of liquid crystal to be dispensed
onto a liquid crystal panel and to control each kind of unit.
[0080] A dispensing amount of liquid crystal is related to a height
of a spacer. In the related liquid crystal vacuum injection method,
a ball spacer is mainly used. However, in the liquid crystal
dispensing method, a pattern spacer or a column spacer is mainly
used for reasons which will be described as follows. As
aforementioned, the liquid crystal dispensing method is mainly used
to fabricate a liquid crystal panel of a large area. When ball
spacers are used in a liquid crystal panel of a large area, it is
difficult to uniformly disperse the ball spacer onto a substrate,
and instead, the dispersed ball spacers mass on the substrate,
thereby causing a cell gap inferiority of the liquid crystal panel.
As a result, in the liquid crystal dispensing method according to
the present invention, a pattern spacer is formed at a preset
position to solve this problem.
[0081] When the height of the pattern spacer formed at the color
filter substrate is different from a preset cell gap, an amount of
liquid crystal contained in the substantially fabricated liquid
crystal panel is different from an optimum liquid crystal amount
even if a preset dispensing amount of liquid crystal is dispensed
onto the substrate because the cell gap becomes different according
to the height of the substantially formed pattern spacer. When the
dispensed amount of liquid crystal is less than the optimum
dispensing amount, for example, with an LCD device of a normally
black mode, a problem is generated in a black brightness, and with
an LCD device of a normally white mode, a problem is generated in a
white brightness.
[0082] In contrast, when the dispensed amount of liquid crystal is
more than the optimum dispensing amount of liquid crystal, a
gravitation inferiority is generated at the time of fabricating a
liquid crystal panel. The gravitation inferiority is generated
accordingly as a volume of a liquid crystal layer formed inside the
liquid crystal panel at the time of fabricating the liquid crystal
panel is increased by a temperature rising. As a result, the cell
gap of the liquid crystal panel becomes greater than the spacer and
liquid crystal moves downward by gravitation, thereby causing an
uneven cell gap of the liquid crystal panel and degrading the
quality of the LCD device.
[0083] The control unit calculates a dispensing amount of liquid
crystal not based on a preset cell gap but based on a substantially
measured spacer height.
[0084] The spacer height is input at the time of a spacer forming
process of a TFT process or a color filter process. That is, in the
spacer forming process, a spacer is formed, and then the spacer
height is measured and provided to the control unit. The spacer
forming line is separately formed from a liquid crystal dispensing
line. As a result, the measured spacer height is input to the
control unit by a wired or wireless connection. Also, the spacer
height may be measured by a separate process. For example, the
spacer height may be measured by providing a spacer height
measuring unit between the spacer forming process line (that is, a
TFT processing line or a color filter processing line) and the
liquid crystal dispensing line, and the measured height may be
input to the liquid crystal dispensing line.
[0085] In FIG. 13, the control unit 200 includes a spacer height
inputting unit 210 for inputting a spacer height measured in the
TFT processing line or the color filter processing line by wire or
wireless connection; an inputting unit 220 for inputting each kind
of information such as a substrate area, a number of panel sheets
to be formed on the substrate, a panel position, a panel area, a
kind of liquid crystal, and a viscosity of liquid crystal; a
dispensing amount calculating unit 230 for calculating a dispensing
amount of liquid crystal to be dispensed onto the liquid crystal
panel based on a pattern spacer height inputted form the spacer
height inputting unit 210 and each kind of information input from
the inputting unit 220; a motor driving unit 240 for operating the
second motor 133 to discharge the calculated dispensing amount,
thereby controlling a fixation angle of the liquid crystal
discharge pump 140; a substrate driving unit 250 for driving the
substrate, thereby moving the liquid crystal dispenser to the
initial dispensing position of a corresponding liquid crystal
panel; and an outputting unit 260 for outputting each kind of
information such as the number of liquid crystal panel sheets
formed on the substrate, a size of a panel on which the current
dispensing is being performed, a dispensing amount of liquid
crystal to be dispensed on a corresponding panel, and the current
liquid crystal dispensing condition.
[0086] The dispensing amount calculating unit 230 calculates a
dispensing amount of liquid crystal to be dispensed onto the liquid
crystal panel based on the panel size, the pattern spacer height,
and the liquid crystal characteristic information. That is, the
dispensing amount calculating unit 230 does not calculate the
dispensing amount of liquid crystal as a glass substrate unit on
which a plurality of liquid crystal panels are formed but
calculates the dispensing amount of liquid crystal as a liquid
crystal panel unit.
[0087] As aforementioned, the dispensing amount of liquid crystal
is calculated as the liquid crystal panel unit to be dispensed onto
the multi-model glass substrate on which the liquid crystal panels
having different sizes are formed. Since the liquid crystal panels
having different sizes are formed on the multi-model glass
substrate, the efficiency of the glass substrate is enhanced,
thereby reducing the fabrication cost. When the plurality of liquid
crystal panels formed on the glass substrate have different cell
gaps (that is, the spacer heights are different from one another),
the dispensing system according to the present invention can be
more effectively applied to dispense liquid crystal onto the
multi-model glass substrate because the dispensing amount of liquid
crystal dispensed onto each liquid crystal panel is calculated
based on the spacer height.
[0088] In FIG. 14, the motor driving unit 240 includes a pulse
value storing unit 244 for storing pulse value information
regarding a dispensing amount of liquid crystal to drive the first
motor 131 and the second motor 133; a pulse value converting unit
242 for converting a calculated dispensing amount value input from
the dispensing amount calculating unit 230 into a pulse value based
on the pulse value information stored in the pulse value storing
unit 244; a first motor driving unit 246 for outputting a driving
signal according to the calculated dispensing amount value is
input, thereby driving the first motor 131 for operating the liquid
crystal discharge pump 140; and a second motor driving unit 248 for
outputting a driving signal for driving the second motor 133
according to the pulse value converted by the pulse value
converting unit 242 is input, thereby varying a fixation angle of
the liquid crystal discharge pump 140.
[0089] Much rotation angle information of the second motor 133
regarding a pulse value is stored in the pulse value storing unit
244. Therefore, as a pulse value is input, the second motor 133 is
rotated as much as a corresponding angle and at the same time, the
liquid crystal capacity amount controlling member 134 inserted into
the rotational shaft 136 is linearly moved. Eventually, by the
motion of the liquid crystal capacity amount controlling member
134, the fixation angle of the liquid crystal discharge pump 140 to
a fixing unit 149 is varied, thereby varying the discharge amount
of liquid crystal from the liquid crystal discharge pump 140. As
aforementioned, the second motor 133 is a step motor and is rotated
one time accordingly as approximately 1000 pulses are input. That
is, the second motor 133 is rotated approximately 0.36.degree. for
one pulse. Therefore, the rotation angle of the second motor 133
can be precisely controlled by a pulse, and the discharge amount of
the liquid crystal discharge pump 140 can be precisely
controlled.
[0090] FIG. 15 shows a liquid crystal dispensing method using a
spacer height. Even if a liquid crystal dispensing method onto the
multi-model glass substrate is illustrated in FIG. 15, a liquid
crystal dispensing method onto one-model glass substrate can be
applied thereto.
[0091] As shown in FIG. 15, a glass substrate including a plurality
of liquid crystal panels having different sizes where a TFT or a
color filter has been formed in the TFT processes or the color
filter processes is input (S301). Herein, each kind of information
regarding the substrate and the liquid crystal panel such as the
substrate size, the number of liquid crystal panel sheets, the size
of each liquid crystal panel, a coordinate of the liquid crystal
panel, and the initial dispensing position is input to the control
unit 200 of the liquid crystal dispenser. Also, liquid crystal
characteristic information such as a kind of liquid crystal and a
viscosity of liquid crystal is input to the control unit 200.
Herein, the liquid crystal information, the substrate information,
and the liquid crystal panel information can be directly input by
the user, and can be input by reading a recognition code such as a
bar code formed on the glass substrate.
[0092] The control unit 200 checks the coordinate and the size of
the liquid crystal panel to which liquid crystal is to be dispensed
based on the input information to recognize a corresponding panel
(S302). In the TFT processes or the color filter processes line, a
pattern spacer is formed on the substrate and the height of the
pattern spacer is measured to be input to the control unit 200
(S303).
[0093] Then, the control unit 200 calculates liquid crystal a
dispensing amount for each liquid crystal panel based on the input
each kind of information input and the spacer height (S304), and
drives the substrate to align the liquid crystal dispenser 120 with
the initial dispensing position of the liquid crystal panel on
which liquid crystal is to be dispensed. Although not shown, since
the substrate is moved in x and y directions by a motor, the motor
is driven to move the substrate to the dispensing position of the
liquid crystal panel. Herein, it is also possible to align the
liquid crystal dispenser 120 with the initial dispensing position
of the liquid crystal panel by directly driving the liquid crystal
dispenser 120 instead of driving the substrate.
[0094] As aforementioned, the liquid crystal dispensing is
performed under the state that the liquid crystal dispenser 120 is
aligned with the dispensing position of the substrate (S305, S306).
Herein, the pulse value converting unit 242 of the motor driving
unit 240 calculates a pulse value corresponding to the calculated
dispensing amount of liquid crystal to drive the second motor 133,
thereby adjusting the fixation angle of the liquid crystal
discharge pump 140. Accordingly, as the first motor 131 is
operated, liquid crystal is dispensed onto the liquid crystal
panel.
[0095] If the liquid crystal dispensing onto a corresponding liquid
crystal panel is completed, the control unit 200 recognizes the
next panel on which liquid crystal is to be dispensed (S307) and
repeats the calculation process of the dispensing amount. That is,
the control unit 200 calculates the dispensing amount of liquid
crystal based on the spacer height formed on the corresponding
panel and each kind of information to dispense liquid crystal onto
the corresponding liquid crystal panel.
[0096] As aforementioned, in accordance with embodiments of the
present invention, the dispensing amount of liquid crystal is
calculated based on the spacer height formed in the TFT processes
or the color filter processes. As a result, the inferiority of the
LCD device due to an inaccurate liquid crystal dispensing can be
prevented. Also, in accordance with embodiments of the present
invention, the dispensing amount of liquid crystal is calculated
for each liquid crystal panel unit, thereby dispensing a precise
amount of liquid crystal onto the multi-model glass substrate.
[0097] It should be recognized that the present invention may be
varied from the exemplary embodiments shown and described. For
example, the liquid crystal dispensing system may be able to read
information of a liquid crystal container as described in Korean
Patent Application No. 2003-41277, filed Jun. 24, 2003, which is
hereby incorporated by reference. Also, the liquid crystal
dispensing system may have a separable liquid crystal discharging
pump as described in Korean Patent Application No. 2003-41278,
filed Jun. 24, 2003, which is hereby incorporated by reference.
[0098] It will be apparent to those skilled in the art that various
modifications and variations can be made in the liquid crystal
dispensing system and method of dispensing liquid crystal material
using the same of the present invention without departing from the
spirit or scope of the invention. Thus, it is intended that the
present invention cover the modifications and variations of this
invention provided they come within the scope of the appended
claims and their equivalents.
* * * * *